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OxyR is involved in coordinate regulation of expression of fimA and sod genes in Porphyromonas gingivalis.

ABSTRACT: Survival of Porphyromonas gingivalis in the constantly changing oral environment depends on its ability to alter gene expression. We demonstrate here that P. gingivalis activates superoxide dismutase expression in response to oxidative stress and represses expression of FimA, a subunit of major fimbriae. Coordinated expression of fimA and sod is regulated by the redox-sensing transcription factor OxyR. Mutations in the oxyR gene result in a decreased expression of sod and in an elevated expression of fimA. In addition, we provide evidence that regulation of expression of fimA and sod by OxyR is mediated by direct interaction of OxyR and the promoters of these two genes. These results suggest that OxyR plays an important role in regulation of expression of virulence genes in P. gingivalis.

SUBMITTER: Wu J

PROVIDER: S-EPMC2430334 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature

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OxyR is involved in coordinate regulation of expression of fimA and sod genes in Porphyromonas gingivalis.

Wu Jie J Lin Xinghua X Xie Hua H

FEMS microbiology letters 20080318 2

Survival of Porphyromonas gingivalis in the constantly changing oral environment depends on its ability to alter gene expression. We demonstrate here that P. gingivalis activates superoxide dismutase expression in response to oxidative stress and represses expression of FimA, a subunit of major fimbriae. Coordinated expression of fimA and sod is regulated by the redox-sensing transcription factor OxyR. Mutations in the oxyR gene result in a decreased expression of sod and in an elevated expressi ...[more]

PMID: 18355277

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Project description:Fimbriae of Porphyromonas gingivalis are filamentous appendages on the cell surface and are thought to be one of the virulence factors. The fimA gene encoding the subunit protein of fimbriae, fimbrillin (FimA), was classified into four typeable variants (types I to IV). We previously examined the distribution of P. gingivalis in terms of fimA genotypes in periodontitis patients using a fimA type-specific PCR assay. However, some patients harbored P. gingivalis with untypeable fimA. In this study, we have cloned a new type (type V) of fimA from dental plaque samples. P. gingivalis with type V fimA was isolated from dental plaque of a periodontitis patient, and the isolate was named HNA-99. The deduced amino acid sequences were compared with those of type I P. gingivalis ATCC 33277, type II strain HW24D1, type III strain 6/26, and type IV strain HG564, and the homologies were found to be 45, 44, 43, and 55%, respectively. Southern blot analysis showed that the clinical isolate HNA-99 possessed P. gingivalis-specific genes sod and kgp. However, in terms of serological specificities, type V FimA showed a difference from other types of FimA. In addition, type V P. gingivalis bacteria were detected in 16.4% (12 of 73) of the P. gingivalis-positive patients with periodontitis by PCR assay using specific primers. Thus, a new type of fimA gene is now established, and the fimA genotyping could be useful in determining the disease-associated genotypes of P. gingivalis involved in the development of adult periodontitis.

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